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Published byLizbeth Robertson Modified over 9 years ago
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What is RADAR? What is RADAR? Active detecting and ranging sensor operating in the microwave portion of the EM spectrum Active detecting and ranging sensor operating in the microwave portion of the EM spectrum Measures backscatter influenced by: Measures backscatter influenced by: ‘Side looking’ with polarization capabilities ‘Side looking’ with polarization capabilities i. i.Dielectric properties ii. ii.Incidence angle iii. iii.Structural properties iv. iv.Polarization v. v.Frequency
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RADAR and Biomass Biomass is positively correlated with SAR backscatter Biomass is positively correlated with SAR backscatter The relationship is almost exactly linear, as backscatter intensity increases, biomass increases. The relationship is almost exactly linear, as backscatter intensity increases, biomass increases.
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RADAR and Biomass (cont) Forest scattering types, a parameter within the biomass regression, varies between forest cover types: Forest scattering types, a parameter within the biomass regression, varies between forest cover types: i. i.Surface and volume scattering from the tree crown ii. ii.Ground-to-trunk scattering iii. iii.Direct ground scattering iv. iv.Direct trunk scattering v. v.Ground-to-crown scattering
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Limitations and benefits of RADAR Limitations and benefits of RADAR Limitations Single band Single band Sloping terrain Sloping terrain Structure specific- young vs old stands Structure specific- young vs old stands Possible saturation level Possible saturation level Speckle Speckle Layering and Shadowing Layering and Shadowing Benefits Atmospheric interactions Atmospheric interactions Canopy Penetration Canopy Penetration Correlation with backscatter Correlation with backscatter Accuracy dependent on data and information of forest type Accuracy dependent on data and information of forest type Active sensor Active sensor
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Application of RADAR and Biomass Research on the possibility of operating a P-band SAR from a satellite to produce a consistent global map of the Earth's forests, in particular for mapping variations in biomass levels for use in global carbon cycle and climate change studies Research on the possibility of operating a P-band SAR from a satellite to produce a consistent global map of the Earth's forests, in particular for mapping variations in biomass levels for use in global carbon cycle and climate change studies Estimated biomass (in tons/ha) from an AIRSAR image of the Manu National Park in Peru in the Amazonian rain forest Regressions with error ranging from 10-24%
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Application of RADAR and Biomass Using SAR imaging to locate individual trees Using SAR imaging to locate individual trees Trees are represented by bright spots. Black circles indicate ground data of tree locations Location and size of individual trees can help determine structure of the forest to get better biomass estimates
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What is LIDAR? LIDAR (Light Detection and Ranging) is an active, high resolution laser scanner generally using NIR wavelengths LIDAR (Light Detection and Ranging) is an active, high resolution laser scanner generally using NIR wavelengths LIDAR sends a short pulse of laser light energy and measures time until return to determine elevation and stores as (x,y,z) LIDAR sends a short pulse of laser light energy and measures time until return to determine elevation and stores as (x,y,z) Some also record the "waveform" of the returned signal, which reveals where—in the space between the ground and the tree tops—the foliage, trunk, and branches are concentrated, multiple layers Some also record the "waveform" of the returned signal, which reveals where—in the space between the ground and the tree tops—the foliage, trunk, and branches are concentrated, multiple layers Several thousand laser pulses are fired every second leaving the aircraft the size of an eraser and hitting the ground at least 75 feet in diameter Several thousand laser pulses are fired every second leaving the aircraft the size of an eraser and hitting the ground at least 75 feet in diameter
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LIDAR Process
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Transects
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LIDAR and Biomass LIDAR is able to process the initial return of the laser plus 5 subsequent returns for multiple layers of biomass LIDAR is able to process the initial return of the laser plus 5 subsequent returns for multiple layers of biomass LIDAR waveforms are placed together into volumetric units LIDAR waveforms are placed together into volumetric units Mathematical models estimate biomass given the 3D image and forest cover data Mathematical models estimate biomass given the 3D image and forest cover data
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Limitations and Benefits of LIDAR and Biomass Benefits Active, high resolution, laser sensor Active, high resolution, laser sensor Canopy layering Canopy layering Biomass by layer and type Biomass by layer and type Stem vs. Leaf vertical biomass Stem vs. Leaf vertical biomass Location accuracy Location accuracy Topology mapping Topology mapping Limitations Atmospheric interactions Atmospheric interactions Cost and data availability Cost and data availability Digital space Digital space Plot size limitations Plot size limitations
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LIDAR application Ecosystem mapping in the tropical rainforests of South America Ecosystem mapping in the tropical rainforests of South America Aerial Photo Final LIDAR return of ground terrain 1 st LIDAR return of Canopy
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LIDAR application (cont) City applications with LIDAR have also surfaced City applications with LIDAR have also surfaced LIDAR image Aerial photo
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Conclusion
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